TCDA/zinc oxide nanocomposites and film sensors

ABSTRACT

Novel TCDA/ZnO compositions in which the ZnO particles have an average particle size less than 100 nm are disclosed. Reversible thermochromatic sensors employing the TCDA nanocomposites and methods of printing TCDA/ZnO nanocomposite thin films forming the reversible thermochromatic sensors using inkjet printing techniques are also disclosed.

FIELD OF THE INVENTION

The present invention relates to the field of sensors, more specificallythe area of TCDA/ZnO nanocomposite film sensors.

BACKGROUND OF THE INVENTION

Materials that change color in response to external stimuli are known as“chromic materials”. Such chromic materials may radiate, lose color, orchange properties induced by external stimuli. Different stimuli resultin different responses in the material being affected.

Polydiacetylenes (“PDAs”) are a series of conjugated polymers which canundergo thermochromic transitions when exposed to temperature stimuli.PDAs have a one-dimensional conjugated backbone with a strong π to π*absorption band in the red spectral region of the optical spectrum whichgives rise to an intense blue color in the polymer. The blue phaseundergoes a temperature-induced or thermochromic transition observed inmany PDAs to a red phase on heating. The blue to red chromatictransition is either irreversible or reversible under heating andcooling cycles depending on the chemical structure and interactions onthe side chains of the PDA. In the blue phase, the strain induced byhydrogen bonding at the head groups leads to an increase in π-electronconjugation length. However, when hydrogen bonding interactions aredisrupted by heat, the side group strain is released leading to twistingof the π-electron orbitals, decrease of π-electron conjugation andconcomitant transition to a red phase. The red phase can rapidly reverseback to the blue phase on cooling when interactions due to: (a) stronghead aromatic groups, (b) ionic moieties, and (c) covalent bond,enhanced hydrogen and multibonding bonding at the head groups arepresent in the PDA structures. The red phase is irreversible when thehead group interactions cannot be restored on cooling. These PDAs aretherefore either irreversible or reversible sensors.

Inkjet printing processes include several well-known attributes,including providing a non-contact and low cost method of fabrication,the ability to deposit precise amount of materials in a rapid way, theability to print on specific locations which is controlled by computer,low temperature processing with no need for a vacuum and compatibilitywith various substrates.

SUMMARY OF THE INVENTION

Novel TCDA/ZnO compositions are disclosed in which the Zn is nanosized,having an average particle size of less than 100 nm. These novelcompositions are sometimes referred to herein as “nanocomposites”.Reversible thermochromatic sensors employing the TCDA/ZnO nanocompositesand methods of printing TCDA/ZnO nanocomposite thin films forming thereversible thermochromatic sensors using inkjet printing techniques arealso disclosed.

In the disclosed TCDA/ZnO nanocomposite compositions TCDA may be presentin an amount of 6 to 99.5 weight percent (wt %) based on the totalweight of the composition. In one embodiment TCDA may be present in anamount of 20 to 99.5 weight percent (wt %) based on the total weight ofthe composition. In another embodiment TCDA may be present in an amountof 50 to 97.5 weight percent (wt %) based on the total weight of thecomposition. In yet another embodiment TCDA may be present in an amountof 85 to 97.5 weight percent (wt %) based on the total weight of thecomposition.

ZnO may be present in an amount of from 0.5 to 94.0 wt %. In oneembodiment ZnO is present in an amount of from 0.5 to 80.0 wt %. Inanother embodiment ZnO is present in an amount of from 2.5 to 50.0 wt %.In another embodiment ZnO is present in an amount of from 2.5 to 15.0 wt%. In one embodiment ZnO is present in an amount of from 5.0 to 15.0 wt%. The ZnO is nanoparticle-sized having an average particle size of0.01-99 nm, more preferably 0.1-99 nm, more preferably 0.1-15 nm.

In one embodiment, thermochromically reversible compositions includingpoly-10,12-tricosadiynoic acid (poly-TCDA) and 2.5 wt % or more of ZnOhaving a particle size range less than 100 nm are disclosed. Theinventors have surprisingly found that while in pure poly-TCDA, heatingabove the chromatic blue to red transition temperature forms anirreversible red phase, poly-TCDA composites with nanosize ZnO displayrapid chromatic reversibility.

In another embodiment, thermochromically reversible compositions aredisclosed which include poly-TCDA and 2.5-15 wt % or more of ZnO havinga particle size range less than 100 nm.

In another embodiment, thermochromically reversible compositions aredisclosed which include poly-TCDA and 5-15 wt % or more of ZnO having aparticle size range less than 100 nm.

In yet a further embodiment thermochromically reversible compositionsare disclosed which consist of poly-TCDA and 2.5-15 wt % of ZnO having aparticle size range less than 100 nm.

In another embodiment, thermochromically reversible compositions aredisclosed which consist of poly-TCDA and 5-15 wt % or more of ZnO havinga particle size range less than 100 nm.

In one embodiment novel nanocomposite inks for thin film applicationsdisclosed herein are made by dispersing a precursor TCDA monomer in theabsence of and/or in the presence of stabilizing agents utilizingaqueous and non-aqueous media as the continuous phase. The reversibilityof chromatic transition may be attained by changing the ratio of TCDA tonanosized ZnO. The chromatic transition properties may be variedaccording to the particle size of ZnO, stabilizer type and dispersingmedia.

In still a further embodiment, compositions are disclosed which includea suspension of TCDA and 0.5-94 wt % of ZnO having a particle size rangebelow 100 nm. Such suspensions may be applied to substrates usingconventional inkjet printing. In a further embodiment an ink compositionconsists of a suspension of TCDA and 2.5-15 wt % of ZnO having aparticle size range below 100 nm in chloroform.

The formulated inks may be fit for a variety of inkjet printingprocesses. For example, in one embodiment the formulated ink is fit for10 picoliter inkjet printing. The disclosed TCDA/ZnO nanocomposites mayfulfill completely/partially reversible color change responding totemperature stimulus. The composites may also be applied in thedetection of chemical solvent.

Methods disclosed herein provide a fast method in ionic bondstrengthened PDA thin film fabrication. In some embodiments the methodspermit inkjet printing of a relatively high concentration TCDA-ZnOsuspension without using surfactant on a flexible substrate

In yet a further embodiment poly-TCDA/ZnO thin film sensors aredisclosed. Thermochromically reversible film sensors may includepoly-TCDA and ZnO nanoparticles disposed on a substrate wherein the ZnOnanoparticles have an average particle size of 0.01-99 nm. In oneembodiment thermochromically reversible film sensors are provided whichinclude a substrate and a film consisting of poly-TCDA and ZnOnanoparticles disposed on the substrate wherein the ZnO nanoparticleshave an average particle size of 0.01-99 nm. The thermochromicallyreversible film sensors may consist of TCDA and 0.5-94 wt % of ZnO.

An information storage thermal sensor is provided having at least aportion thereof comprising a thermochromic composition. In oneembodiment the sensor includes a QR code.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

So that those having ordinary skill in the art will have a betterunderstanding of how to make and use the disclosed systems and methods,reference is made to the accompanying figures wherein:

FIG. 1A is a graphical depiction of ATR-FTIR spectra at room temperatureof pure poly-TCDA in the blue and red phases in accordance with anembodiment of the presently disclosed subject matter;

FIG. 1B is a graphical depiction of ATR-FTIR spectra at room temperatureof poly-TCDA and poly-TCDA/ZnO in the blue phase for two concentrationsof ZnO between 700 and 3300 cm-1 in accordance with an embodiment of thepresently disclosed subject matter;

FIG. 1C is a graphical depiction of ATR-FTIR spectra according to FIG.1B expanded in the 750 and 1800 cm-1 spectral range, respectively;

FIG. 2A is a graphical depiction 785 nm laser-excited Raman spectra ofblue (bottom) and red (top) phases of poly-TCDA at room temperature inaccordance with an embodiment of the presently disclosed subject matter;

FIG. 2B is a graphical depiction of blue phase of poly-TCDA andpoly-TCDA/ZnO composites with three different ZnO concentrations atambient temperature in accordance with an embodiment of the presentlydisclosed subject matter;

FIGS. 3A and 3B are graphical depictions of 785 nm laser excited Ramanspectra of pure poly-TCDA as a function of increasing temperature (FIG.3A) and decreasing temperature (FIG. 3B) in accordance with anembodiment of the presently disclosed subject matter;

FIGS. 4A and 4B are graphical depictions of 785 nm laser excited Ramanspectra of poly-TCDA/ZnO (5 wt %) as a function of increasingtemperature (FIG. 4A) and decreasing temperature (FIG. 4B) in accordancewith an embodiment of the presently disclosed subject matter;

FIGS. 5A and 5B are graphical depictions of 785 nm laser excited Ramanspectra of poly-TCDA/ZnO (15 wt %) as a function of increasingtemperature (FIG. 5A) and decreasing temperature (FIG. 5B) in accordancewith an embodiment of the presently disclosed subject matter;

FIGS. 6A-6D are graphical depictions of temperature dependence onheating and cooling of the polymer backbone C≡C and C═C stretching modefrequencies of poly-TCDA and poly-TCDA/ZnO composites with different ZnOcontents in accordance with an embodiment of the presently disclosedsubject matter;

FIGS. 7A-7D are graphical depictions of heating DSC scans for a TCDAmonomer (FIG. 7A); poly-TCDA (FIG. 7B—the slightly broadened transitionis due to unpolymerized monomer); ZnO nanopowder (<100 nm)(FIG. 7C); andTCDA monomer/ZnO nanocomposites (FIG. 7D) of three differentcompositions in accordance with an embodiment of the presently disclosedsubject matter;

FIG. 8A is a schematic depiction of chromaticity (chroma) distributionfrom gray (dull) color at the center to saturated (vivid) color at theperimeter (arrows indicate chromatic transition temperatures discussedin the text);

FIG. 8B is a graphical depiction of chromaticity versus temperature forpoly-TCDA and poly-TCDA/ZnO composites of three different compositionsin accordance with an embodiment of the presently disclosed subjectmatter;

FIG. 8C is a graphical depiction of chromaticity of poly-TCDA/ZnO (5 wt%) as a function of thermal cycle in accordance with an embodiment ofthe presently disclosed subject matter;

FIG. 8D is a graphical depiction of chromaticity of poly-TCDA/ZnO (15 wt%) as a function of thermal cycle in accordance with an embodiment ofthe presently disclosed subject matter;

FIG. 9A and FIG. 9B are graphical depictions of polymerization of TCDA:TCDA (FIG. 9A) and poly-TCDA after UV radiation (FIG. 9B) in accordancewith an embodiment of the presently disclosed subject matter;

FIG. 10A and FIG. 10B are photographic depictions of photos of inkjetprinted TCDA monomer before UV radiation (FIG. 10A) and after UVradiation (FIG. 10B) in accordance with an embodiment of the presentlydisclosed subject matter;

FIGS. 11A-11C are graphical depictions of ATR-FTIR spectra at roomtemperature of Pure poly-TCDA in the blue and red phases (FIG. 11A);poly-TCDA and poly-TCDA-ZnO in the blue phase between 700 and 3300 cm⁻¹(FIG. 11B) and expanded in the 750 and 1800 cm⁻¹ spectral range (FIG.11C) in accordance with an embodiment of the presently disclosed subjectmatter;

FIG. 12 is a graphical depiction of 785 nm laser-excited Raman spectraof the inkjet printed blue (bottom) and red (top) phases of poly-TCDA atroom temperature) in accordance with an embodiment of the presentlydisclosed subject matter;

FIG. 13 is a graphical depiction of Raman spectra of pure poly-TCDA andpoly-TCDA-ZnO thin film fabricated by inkjet printing in accordance withan embodiment of the presently disclosed subject matter;

FIGS. 14A and 14B are graphical depictions of 785 nm laser excited Ramanspectra of pure poly-TCDA as a function of increasing temperature (FIG.14A) and decreasing temperature (FIG. 14B) in accordance with anembodiment of the presently disclosed subject matter;

FIGS. 15A and 15B are graphical depictions of 785 nm laser excited Ramanspectra of poly-TCDA-ZnO (2.5 wt %) as a function of increasingtemperature (FIG. 15A) and decreasing temperature (FIG. 15B) inaccordance with an embodiment of the presently disclosed subject matter;

FIGS. 16A and 16B are graphical depictions of C≡C and C═C wavenumbers ofpoly-TCDA and poly-TCDA-ZnO, respectively, as a function of temperaturein accordance with an embodiment of the presently disclosed subjectmatter;

FIGS. 17A-D are graphical depictions of DSC heating scans for TCDA (FIG.17A), poly-TCDA (FIG. 17B), ZnO (<100 nm) powder (FIG. 17C) andpoly-TCDA-ZnO (FIG. 17D) in accordance with an embodiment of thepresently disclosed subject matter;

FIG. 18 is a graphical depiction of chromaticity versus temperatureplots for poly-TCDA and poly-TCDA-ZnO composite film in accordance withan embodiment of the presently disclosed subject matter;

FIG. 19 is a graphical depiction of difference of chromaticity ofpoly-TCDA and poly-TCDA-ZnO every five heating-cooling cycles inaccordance with an embodiment of the presently disclosed subject matter;

FIGS. 20A-D are photographic depictions of 5 mm×5 mm square patternedpoly-TCDA and poly-TCDA-ZnO fabricated by inkjet printing (5-layerprinting): poly-TCDA-ZnO at room temperature (FIG. 20A); poly-TCDA-ZnOat 80° C. (FIG. 20B); poly-TCDA-ZnO at 25° C. after 40 cycles (FIG.20C); poly-TCDA at 25° C. after 5 cycles (FIG. 20D) in accordance withan embodiment of the presently disclosed subject matter; and

FIGS. 21A-21B are photographic depictions of QR codes with partial areaof poly-TCDA/ZnO fabricated by inkjet printing methods in accordancewith an embodiment of the presently disclosed subject matter.

DETAILED DESCRIPTION OF THE INVENTION

The following is a detailed description of the invention provided to aidthose skilled in the art in practicing the present invention. Those ofordinary skill in the art may make modifications and variations in theembodiments described herein without departing from the spirit or scopeof the present invention. Unless otherwise defined, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. The terminology used in the description of the invention hereinis for describing particular embodiments only and is not intended to belimiting of the invention. All publications, patent applications,patents, figures and other references mentioned herein are expresslyincorporated by reference in their entirety.

Thermochromically reversible compositions including TCDA and nanosizeZnO having a particle size range less than 100 nm are disclosed. Theinventors have surprisingly found that while in pure poly-TCDA, heatingabove the chromatic blue to red transition temperature forms anirreversible red phase, poly-TCDA composites with nanosize ZnO displayrapid chromatic reversibility. The nanosized ZnO is preferablyunalloyed.

Compositions disclosed herein may be incorporated into the form of anink, paint, spray or other type of coating for subsequent applicationand use. Accordingly, any conventional components required for theproduction of such ink, paint, etc. may be included, such as polymericbinders, plasticizers, UV absorbents, etc.

TCDA may be present in an amount of 6 to 99.5 weight percent (wt %)based on the total weight of the composition. In one embodiment TCDA maybe present in an amount of 20 to 99.5 weight percent (wt %) based on thetotal weight of the composition. In another embodiment TCDA may bepresent in an amount of 50 to 97.5 weight percent (wt %) based on thetotal weight of the composition. In yet another embodiment TCDA may bepresent in an amount of 85 to 97.5 weight percent (wt %) based on thetotal weight of the composition.

ZnO may be present in an amount of from 0.5 to 94.0 wt %. In oneembodiment ZnO is present in an amount of from 0.5 to 80.0 wt %. Inanother embodiment ZnO is present in an amount of from 2.5 to 50.0 wt %.In another embodiment ZnO is present in an amount of from 2.5 to 15.0 wt%. In one embodiment ZnO is present in an amount of from 5.0 to 15.0 wt%. The ZnO is nanoparticle-sized having an average particle size of0.01-99 nm, more preferably 0.1-99 nm, more preferably 0.1-15 nm.

Syntheses of the presently disclosed TCDA and nanosized ZnO compositionswere carried out on a laboratory scale. A representative process forpreparation of a poly-TCDA and ZnO composition is disclosed in theexperiments hereinbelow.

In one embodiment flexible reversible color change poly-TCDA-ZnOcomposite-based chromatic sensors are disclosed. Substrates may includeany substrate that is amenable to inkjet printing, such as but notlimited to paper, cloth, polymer, glass, etc.

For example, a poly-TCDA based sensor was made using a Fujifilm Dimatixprinter model DMP-2800 which is based on piezoelectric inkjettechnology. A cartridge with a nozzle pore size of ca. 20 μm diameterwas filled with a TCDA/chloroform solution or suspension of the TCDA-ZnOin chloroform and the ink was printed on unmodified. After inkjetprinting the printed images were formed following solvent evaporation at40° C. The inkjet-printed TCDA and TCDA/ZnO composites were polymerizedto the blue phase of poly-TCDA composites by irradiating with a 254 nmwavelength UV source after inkjet printing. Red phase poly-TCDA wasprepared by heating up the inkjet printed pattern to chromatictransition temperature. Attenuated Total Reflection (ATR)-FourierTransform Infrared (FTIR) results showed chelate formation between TCDAand ZnO. In one embodiment, a film sensor of poly-TCDA-ZnO (2.5 wt %) ona flexible substrate was produced with reversible chromatic transitionfrom 25° C. to 80° C., which cannot be found in pure poly-TCDA.Temperature-dependent Raman spectra indicate the blue-red phase ofpoly-TCDA-ZnO (2.5 wt %) thermal-triggered color change occurs at 70° C.and amorphous phase forms at around 120° C.

An inkjet printed Quick Response (QR) code made using TCDA-ZnO ink asdisclosed herein demonstrates a sensory functionality which can beincorporated into such QR codes.

The presently disclosed TCDA/ZnO nanocomposites are novel, as are theiruses as chromatic sensors and production thereof using inkjet printing.The functionality of the disclosed TCDA/ZnO nanocomposites may bevaried. For example, by changing ratio of TCDA to ZnO, the chromatictransition temperature may be varied.

EXAMPLES AND EXPERIMENTS Experiment 1

Materials. TCDA was purchased from GFS Chemicals and nanocrystalline ZnO(<100 nm diameter) was purchased from Sigma-Aldrich. Analytical gradechloroform was purchased from Sigma-Aldrich and used without furtherpurification.

Synthesis of Poly-TCDA-ZnO Nanocomposites. Poly-TCDA/ZnO suspensionswere prepared by suspending different amounts of ZnO (5 wt %, 10 wt %,15 wt %) in solution of the TCDA monomer (1 mM) in chloroform. Thesuspension contained in a beaker was sonicated in a water bath at roomtemperature for 30 min and dried at 40° C. with magnetic stirring for 8hours. The magnetic stirring was stopped after the liposome state wasachieved. The pure TCDA and TCDA composites were polymerized to the bluephase of poly-TCDA and poly-TCDA-ZnO composite by irradiating with a 254nm wavelength UV source. Powders of the blue phase composite wereobtained by scraping from the beaker and grinding into a fine powder.Red phase composite powders and films were similarly produced afterheating the blue phase to above the thermochromic transitiontemperature.

Raman Spectroscopy. Raman spectra at room temperature were obtainedprimarily using a Mesophotonics Raman spectrometer with 785 nm laserexcitation. Temperature-dependent Raman measurements were carried outwith an EZRaman LE Raman Analyzer system from Optronics using 785 nmlaser excitation coupled to a Leica optical microscope. The spectrometerwas calibrated using silicon wafer and diamond powder standards to afrequency accuracy of 1 cm⁻¹. The variable temperature optical stageused was from Linkam Scientific Instruments Ltd. Thick films for theRaman measurements were prepared by mixing suspensions of TCDA withcertain amount of ZnO, using chloroform as the suspension medium. Afterdrying and 254 nm UV radiation, the polymerized dry powder of poly-TCDAand poly-TCDA/ZnO were measured on a silicon wafer substrate.

ATR-FTIR Spectroscopy. Fourier Transform Infrared (FTIR) was carried outusing a Nicolet ThermoElectron FTIR 560 spectrometer with a MIRacleattenuated total reflectance (ATR) platform assembly and a Ge plate.

Optical Densitometry. Chromaticity, which is a quantitative measure ofthe vividness or dullness of a color (or how close the color is toeither the gray or pure hue) was measured directly on thin film andcoated samples using an X-Rite 518 optical densitometer as the sampleswere heated on a temperature-controlled hot plate.

Differential Scanning Calorimetery (DSC). A Mettler Toledo DSCinstrument (Mettle-Toledo Inc. Columbus, Ohio, USA) with a FP90 centralprocessor was used to obtain the DSC data of 10 mg of precursor, polymerand composite samples wrapped in a small disk with aluminum foil usingheating/cooling/heating cycles in the temperature range from 25° C. to300° C. at a rate of 10° C. min⁻¹.

Attenuated Total Reflection (ATR)-Fourier Transform Infrared (FTIR)spectroscopy at room temperature in both the red and blue phases forpure poly-TCDA and for the blue phase in poly-TCDA/ZnO together withRaman spectroscopy as a function of temperature for poly-TCDA andpoly-TCDA/ZnO provide details about the molecular structural changesaround the chromatic transition and molecular interactions onnanocomposite formation. The thermal and colorimetric changes as afunction of temperature at these transitions are investigated further byDSC and optical densitometry, respectively.

FIG. 1A shows the ATR-FTIR spectra of poly-TCDA in its blue and redphases, and FIGS. 1B and 1C show the spectra of poly-TCDA andpoly-TCDA/ZnO in the 700 to 3500 cm⁻¹ and expanded in the 700 to 1900cm⁻¹ regions, respectively. Lines at 2920 and 2847 cm⁻¹ are assigned tothe asymmetric and symmetric stretching vibrations, respectively, of theCH₂ groups on the side chains, and those at 1463, 1417 and 1694 cm⁻¹ canbe attributed to the CH₂ scissoring and hydrogen-bonded carbonyl C═Ostretching vibrations, respectively. On comparing the FTIR spectra ofpure poly-TCDA with that of poly-TCDA/ZnO shown in FIGS. 1B and 1C, itwas observed that a relatively strong new line appears at 1540 cm⁻¹ inthe spectrum of poly-TCDA/ZnO together with a concomitant decrease inintensity of the C═O stretching line at 1694 cm⁻¹. The 1540 cm⁻¹ linecan be assigned to an asymmetric COO⁻ stretching vibration and itspresence in the spectra together with a corresponding decrease in theintensity of the C═O line suggests that a chelate between neighboringside chain —COOH head groups of poly-TCDA and Zn²⁺ ions from ZnO isformed. This chemical interaction between ZnO and poly-TCDA, dependenton the ionicity of the Zn—O bond is likely to cause the high temperaturered phase to revert to the blue phase on cooling in poly-TCDA/ZnOcomposites.

Raman scattering due to the molecular vibrational modes of theconjugated polymer backbone are expected to be primarilyresonance-enhanced for excitation using 780 nm laser radiation. From theRaman spectra in FIG. 2A for pure poly-TCDA, two intense lines at 2083cm⁻¹ and 1455 cm⁻¹ were observed at room temperature in the blue phase,which can be definitively assigned to the C≡C and C═C stretching modesof the polymer backbone, respectively. The C═C stretching mode is closein frequency to a line at 1463 cm⁻¹ assigned to a side chain CH₂deformation mode observed in the ATR-FTIR spectra in FIG. 1. In the redphase the room temperature C≡C and C═C stretching vibration frequenciesat 2114 cm⁻¹ and 1516 cm⁻¹, respectively, increase due to theirreversible stress on the polymer backbone due to dissociation of thehead group hydrogen bonds in the red phase. The line intensities in thered phase are lower because of decreased resonance interaction with thepolymer backbone. This decrease in resonance interaction with thepolymer backbone in the red phase was not evident in the Raman spectrumof the red phase of PCDA and is likely to be due to the fact that thehydrocarbon side chain is longer in PCDA. The Raman lines at frequenciesbelow that of the C═C stretching mode can be assigned to Raman-activedeformation and C—C stretching motions of the conjugated polymerbackbone mixed with hydrocarbon chain deformation modes. The triplet oflines around 1250 cm⁻¹ and the line at 690 cm⁻¹ in the blue phase arerelatively intense as a result of resonance enhancement due to mixing ofthe backbone C—C stretching and deformation modes.

FIG. 2B shows the Raman spectrum of pure poly-TCDA in the blue phasecompared with the blue phase spectra of poly-TCDA/ZnO composites. Nowreferring to FIGS. 3A and 3B, it is evident that a very weak line at2257 cm⁻¹ in the C≡C stretching mode region of poly-TCDA increases inintensity in the composite. By contrast a relatively weak line in theC═C region at 1516 cm⁻¹ in the blue phase due to a red phase impuritydisappears on composite formation. The line at 2257 cm⁻¹ can be assignedto a diyne defect formed on the backbone due to the chemical interactionbetween TCDA and ZnO. However, the intensity of this line appears tosaturate at low ZnO concentration and does not increase with increasingZnO. Another feature in FIGS. 3A and 3B which is consistent with thechemical interaction of poly-TCDA with ZnO is that the line at 690 cm⁻¹and the triplet of lines at 1250 cm⁻¹ assigned above to largely polymerbackbone modes show substantial increase in intensity in the compositephase.

With reference to FIGS. 3A-5B, Raman spectra under heating and coolingcycles in the 25° C. to 150° C. temperature range for poly-TCDA andpoly-TCDA/ZnO at different ZnO concentrations are shown. The Raman datawere taken in steps of 10° C. from 30° C. to 150° C. and also recordedin 10° C. steps during the cool down to room temperature. FIGS. 3A-3Bdisplay the Raman spectra of poly-TCDA with increasing temperature to150° C. (FIG. 3A) followed by cooling from 140° C. to 30° C. (FIG. 3B).The heat-up spectra in FIG. 3A indicate the backbone stretching anddeformation lines in the blue phase decrease in intensity withincreasing temperature as the sample goes to the red phase consistentwith the fact that resonance-enhancement is weaker in the red phase asdiscussed above. The weak line at 1516 cm⁻¹ assigned to a red phaseimpurity in the blue phase grows in intensity and becomes thepredominant C═C backbone stretching mode in the red phase. FIG. 3B showsthe spectrum remains essentially unchanged on cooling consistent withthe irreversibility of the red phase of poly-TCDA.

The heating and cooling Raman spectra of poly-TCDA/ZnO with the ZnOcontent at 5 wt % are shown in FIGS. 4A and 4B, respectively. Bycontrast with the variable temperature spectra for pure poly-TCDA, abroad scattering band centered near 690 cm⁻¹ appears reproducibly in thespectra with increasing intensity as the temperature approaches and goesabove the ca. 120° C. melting transition of the ZnO composites observedin the DSC data discussed hereinbelow and shown in FIGS. 7A-D. Note thatthe broad scattering feature appears below the melting transitiontemperature and increases in intensity above 120° C. Without beingconfined to a single theory it is believed this is due to lightscattering from an amorphous network of the poly-TCDA/ZnO complex. Thescattering is not seen at higher ZnO concentrations as discussed belowand it is also not observed in poly-PCDA/ZnO at all concentrations ofZnO, most likely because the diffusional motions of the longerhydrocarbon side chain in poly-PCDA compared with poly-TCDA prevents theformation of the amorphous network. The intensity from the amorphousnetwork shows a small decrease on cooling through the meltingtemperature down to room temperature in FIG. 4B. Moreover, the featuresof the spectra in FIG. 4B show that the red phase of the composite with5% by weight of ZnO converts only partially back to the blue phase oncooling.

FIGS. 5A and 5B show the heating and cooling Raman spectra,respectively, of poly-TCDA/ZnO (15 wt %). Similar heating and coolingRaman spectra (not shown) were observed for poly-TCDA/ZnO (10 wt %).Broad scattering due to amorphous poly-TCDA/ZnO at these higher ZnOconcentrations are not observed. Also, the red phase spectrum changesrapidly back to that of the blue phase on cooling.

The Raman frequencies of the C≡C and C═C backbone stretching vibrationsof pure poly-TCDA, poly-TCDA with 5 wt %, 10 wt % and 15 wt % of ZnObelow 100 nm in size as a function of heating and cooling cycles areplotted as a function of temperature in FIGS. 6A-6D. The frequencyupshift in the red phase decreases with increasing ZnO contentsuggesting that the stress on the polymer backbone is lowered due tochelation of ZnO with the head group of poly-TCDA to make the chromatictransition reversible. The plots in FIGS. 6A-6D of the Raman-active C≡Cand C═C backbone stretching frequencies as a function of temperaturecycling indicate increases in frequencies at the chromatic blue to redtransition at 70° C. on heating for pure poly-TCDA and near 120° C. forthe poly-TCDA/ZnO composites. For poly-TCDA/ZnO (5 wt %), the slightupshift of frequency of the C═C and C≡C modes at 70° C. may be due tonon-chelated TCDA monomer. The frequency upshift at 130° C. in thecomposites is due to chelate formation between TCDA and ZnO.

Now referring to FIGS. 7A-7D, differential scanning calorimetry (DSC)measurements provide further understanding of the nature ofTCDA/poly-TCDA/ZnO interactions. DSC data were obtained for pure TCDAmonomer, poly-TCDA, and poly-TCDA/ZnO, at heating and cooling rates of10° C. min⁻¹ between 25° C. and 300° C. The heating scan for pure TCDAin FIG. 7A shows an endothermic peak at 61° C. due to melting. Oncooling (scan not shown here) down-shifted exothermic crystallizationpeaks at 59° C. due to hysteresis were observed. The heating scan forpoly-TCDA in FIG. 7B shows an endothermic peak at 61° C. due to meltingof the unpolymerized monomer. A broad endotherm with a shoulder at 154°C. and a peak at 190° C. are assigned to the melting of poly-TCDA. Oncooling (scan not shown), polymer crystallization is indicated by broadexothermic features at 159° C. and 194° C. which are upshifted due tohysteresis relative to the corresponding endothermic melting peaks.Crystallization of unpolymerized monomer was not observed during thecooling cycle probably due to loss of the monomer by sublimation duringthermal cycling. The heating scans for TCDA-ZnO nanocomposites in FIG.7D show endotherm around 57° C. due to unpolymerized monomer and a newendothermic feature at around 137° C. due to melting of the monomermodified by chelate formation with ZnO discussed above. It is also seenfrom FIG. 7D that with the increase of ZnO content, the endotherm due toTCDA becomes weaker and the peak shifts to higher temperature indicatingthat the chelate between ZnO and head group —COOH becomes strongerbecause more chelate formation can occur with increasing ZnO content.This is consistent with the FTIR, Raman and DSC data discussed abovesuggesting an interaction of ZnO particles with the head group of thepolymer side-chain to form a chelate which can be schematically writtenas: Zn²⁺(COO⁻)₂. In pure poly-TCDA, heating causes an irreversiblestress on the polymer backbone due to the dissociation of hydrogen bondsbetween the side chain head groups to form the red phase. In thepresence of ZnO, chelate formation results in release of strain oncooling and reversal to the blue phase.

The changes in chromaticity for different samples shown in FIG. 8B as afunction of temperature further verifies the interaction betweenpoly-TCDA and ZnO with increase of ZnO content from 5 wt % to 15 wt %.The rapid increase followed by a drop of the chromaticity of poly-TCDAis caused by the chromatic transition near 70° C. 5 wt % ZnO increasesthe chromatic transition to 120° C. consistent with the Raman data. Thepoly-TCDA/ZnO composites with 10 wt % and 15 wt % have almost the samecorrelation of chromaticity and temperature which indicates that thereis a critical ZnO content to form the chelate between TCDA and ZnO.FIGS. 8C and 8D show fairly good reversibility in chromaticity as afunction of number of cycles from 25° C. to 80° C. and from 25° C. to150° C. indicating that the nanocomposite can function as a veryreproducible thermal sensor.

Thus, Raman, FTIR, DSC and colorimetric measurements confirm thethermochromic reversibility introduced by composite formation ofpoly-TCDA with ZnO in the particle size range below 100 nm. Ramanfrequency upshifts occur at 70° C. and 120° C. in pure poly-TCDA andpoly-TCDA/ZnO composites, respectively, corresponding to chromatictransitions. The peak shifts of the Raman-active υ(C≡C) and υ(C═C)vibration peaks increase with increase of ZnO content. Poly-TCDA/5 wt %ZnO shows only partially reversible color change, whereas poly-TCDA/10wt % ZnO and poly-TCDA/15 wt % ZnO change color reversibly and havesimilar thermochromic responses. The Raman data indicate theirreversible formation of an amorphous poly-TCDA phase in poly-TCDA/5 wt% ZnO but not in poly-TCDA composites with 10 wt % and 15 wt % ZnO.Chelate formation between ZnO and neighboring side chain —COOH headgroups leads to reversibility of the chromatic transition and increaseof the chromatic transition temperature. Excellent reversibility inchromaticity as a function of number of cycles from 25° C. to 80° C. andfrom 25° C. to 150° C. is observed indicating that the poly-TCDA/ZnOnanocomposites may function as a temperature sensor.

Experiment 2

Materials. TCDA was purchased from GFS Chemicals and nanocrystalline ZnO(<100 nm diameter) was purchased from Sigma-Aldrich. Analytical gradechloroform (>99%) was purchased from Sigma-Aldrich and used withoutfurther purification.

Preparation of TCDA/TCDA composite inks. TCDA was purified by dissolvingand removing the polymerized solid. TCDA composite inks were prepared bysuspending 5 wt % ZnO in TCDA/chloroform solution with the ratio ofTCDA/chloroform 0.1 mol/50 ml. The suspension was sonicated in a waterbath at room temperature for 15 minutes, then rested for 1 hour toenable removal of unsuspended ZnO particles (2.5 wt % of the TCDA).

Design and fabrication of poly-TCDA based chromatic sensor. The designand fabrication of the poly-TCDA based sensor was performed using aFujifilm Dimatix printer model DMP-2800 which is based on piezoelectricinkjet technology. The cartridge with a nozzle pore size of ca. 20 μmdiameter was filled with a TCDA/chloroform solution or suspension of theTCDA-ZnO in chloroform and the ink was printed on unmodified A4-sizedpaper. Both TCDA and TCDA/ZnO were inkjet printed with 20 volt appliedon nozzle pores. Nozzle cleaning was carried out every 5 bands ofprinting. After inkjet printing either TCDA or TCDA/ZnO compositesuspension on a flexible substrate, the printed images were formedfollowing solvent evaporation at 40° C. The pattern for Raman andoptical densitometry measurements was designed in a square shape (5 mm×5mm).

Synthesis of poly-TCDA-ZnO nanocomposites. The TCDA and TCDA/ZnOcomposites inkjet printed on a substrate were polymerized to the bluephase of poly-TCDA composites by irradiating with a 254 nm wavelength UVsource after inkjet printing. FIGS. 9A and 9B illustrate thepolymerization reaction of TCDA under UV exposure. Red phase poly-TCDAwas prepared by heating up the inkjet printed pattern to chromatictransition temperature.

Material Characterization

Raman spectroscopy. Room temperature Raman spectra of thin filmsfabricated by inkjet printing were obtained primarily by using aMesophotonics Raman spectrometer with 785 nm laser excitation.Temperature-dependent Raman measurements for the inkjet printed patternswere carried out with an EZRaman LE Raman Analyzer system from Optronicsusing 785 nm laser excitation coupled to a Leica optical microscope. Thespectrometer was calibrated using silicon wafer and diamond powderstandards to a frequency accuracy of 1 cm⁻¹. The variable temperatureoptical stage used was from Linkam Scientific Instruments Ltd. Thinfilms for the Raman measurements were prepared by 5-layer inkjetprinting the suspensions of TCDA/ZnO in chloroform on silicon wafer.After 254 nm uv-radiation, the polymerized TCDA and poly-TCDA-ZnO weremeasured directly.

ATR-FTIR spectroscopy. Fourier Transform Infrared (FTIR) was carried outusing a Nicolet ThermoElectron FTIR 560 spectrometer with a MIRacleattenuated total reflectance (ATR) platform assembly and a Ge plate.Poly-TCDA powder was acquired by scratching off the inkjet printedpoly-TCDA/composites on Kapton film. The inkjet printing parameters werethe same as that of paper substrate inkjet printing.

Optical densitometry. Chromaticity was measured directly on printed filmusing an X-Rite 518 optical densitometer as the film was heated on atemperature-controlled hot plate.

Differential scanning calorimetery (DSC). A Mettler Toledo DSCinstrument with a FP90 central processor was used to obtain the DSC dataof inkjet printed precursor, polymer and composites. 10 mg of powderwrapped in a small disk with aluminum foil was subjected toheating/cooling/heating cycles in the temperature range from 25° C. to300° C. at a rate of 10° C. min⁻¹.

As noted above, ZnO can form chelate with neighboring side chain —COOHhead groups of poly-TCDA which results in reversible chromatictransition and an increase of the chromatic transition temperature. Thepresent inventors have further found inkjet printing processes do notchange the functionality of the disclosed poly-TCDA and poly-TCDA/ZnOfilms.

Inkjet printing TCDA and TCDA/ZnO composites. Now referring to FIG. 10A,TCDA ink applied to a substrate using an inkjet printer as describedaccording to the present disclosures is not visible when it is in themonomer state because TCDA do not absorb visible light. However, uponpolymerization with UV radiation (254 nm, 1 mW/cm 2, 30 s) blue imagepatterns are formed (FIG. 10B). This indicates PDA monomers arewell-aligned and closely packed following printing and that PDAs areindeed generated on the paper. This is an important result since if theclosely packed alignment of the PDA monomers were disrupted during theprinting and fixing steps, polymerization would not proceed.

Raman and ATR-FTIR Spectroscopy of Poly-TCDA and Composites. Themolecular structural changes of the chromatic transition and molecularinteractions on nanocomposites formation are studied by ATR-FTIR andRaman spectroscopy at room temperature in both the red and blue phasesfor pure poly-TCDA and for the blue phase in poly-TCDA/ZnO. Nowreferring to FIG. 11A, ATR-FTIR spectra of poly-TCDA is shown in theblue and red phases. With further reference to FIGS. 11B and 11C,spectra are depicted of poly-TCDA and poly-TCDA-ZnO in the frequencyregion from 700 to 3300 cm⁻¹ and the expanded spectra from 700 to 1900cm⁻¹ frequency regions, respectively. As in the first experiment, linesat 2920 and 2847 cm⁻¹ were assigned to the asymmetric and symmetricstretching vibrations, respectively, of the CH₂ groups of thehydrocarbon side chains on poly-TCDA, and those at 1463, 1417 and 1694cm⁻¹ attributed to the CH₂ scissoring and hydrogen-bonded carbonyl C═Ostretching vibrations, respectively. On comparing the FTIR spectra ofpure poly-TCDA with that of poly-TCDA/ZnO shown in FIGS. 11B and 11C, arelatively strong line appears at 1540 cm⁻¹ in the spectrum ofpoly-TCDA-ZnO together with a decrease in intensity of the C═Ostretching line at 1694 cm⁻¹. The 1540 cm⁻¹ line can be assigned to anasymmetric COO⁻ vibration and its presence in the spectra indicates theformation of a chelate between the side chain —COOH head groups ofpoly-TCDA and Zn²⁺ from ZnO.

780 nm laser excited Raman spectra were obtained to probe theresonance-enhanced molecular vibrational modes of the conjugated polymerbackbone. From the Raman spectra in FIG. 12 and Table 1 for purepoly-TCDA, two primary lines at 2083 cm⁻¹ and 1455 cm⁻¹ are observed atroom temperature in the blue phase, which can be clearly assigned to theC≡C and C═C stretching modes of the polymer backbone, respectively. Inthe red phase at 25° C., the C≡C and C═C stretching vibrationfrequencies show up at 2114 cm⁻¹ and 1516 cm⁻¹, respectively. Comparedwith those in blue phase, the upshift in frequency is due to theirreversible stress on the polymer backbone caused by the breakup of thehead group hydrogen bonds in the red phase.

TABLE 1 C≡C and C═C Raman peak frequencies in pure poly-TCDA and inpoly-TCDA-ZnO nanocomposites in the blue and red phases. Poly-TCDA/ZnO(2.5 wt %) Poly-TCDA, 25° C. [Blue, 25° C.; Red, 150° C.] Phase υ(C≡C)cm⁻¹ υ(C≡C) cm⁻¹ υ(C≡C) cm⁻¹ υ(C≡C) cm⁻¹ Blue 2083 1455 2081 1453 Red2118 1516 2108 1507

Now referring to FIG. Raman spectrum of pure poly-TCDA in the blue phaseis compared with the blue phase spectra of poly-TCDA-ZnO compositesprepared by the presently disclosed inkjet printing method. A very weakline at 2257 cm⁻¹ in the C≡C stretching mode region of poly-TCDA showsup in the Raman spectra of poly-TCDA/ZnO, which can be assigned to adiyne formed as a defect on the backbone due to the interaction betweenTCDA and ZnO. Similar to the poly-TCDA prepared above, the line at 1516cm⁻¹ shows up in the pure poly-TCDA fabricated by inkjet printing whichcould be attributed to the presence of a red phase impurity in themajority blue phase. Another feature in FIG. 13 which is similar to theprevious experiment is that the line at 690 cm⁻¹ and the triplet oflines at 1250 cm⁻¹ assigned above to polymer backbone modes, showsubstantial decrease in intensity with composite formation, meanwhile abump shows up around line at 690 cm⁻¹. These phenomena could be due tothe increase of disorder degree in long molecular range caused by theformation of chelate between ZnO and partial C═O groups and thedisordered molecular arrangement reduces resonance interaction with thepolymer backbone. By comparison with poly-TCDA in Table 1, the Ramanfrequency upshift of the C≡C and C═C backbone stretching vibrations inred phases decreases in the presence of ZnO, which suggests that thebackbone stress is lowered due to the interaction of ZnO with poly-TCDA.

Analysis of ATR-FTIR and Raman spectra further shows that inkjetprinting does not affect the close packing alignment of TCDA moleculesand demonstrates the feasibility of polymerization after TCDA is inkjetprinted on a paper substrate. The ATR-FTIR and Raman spectra indicatethe interaction between TCDA and ZnO. Compared with poly-TCDA andpoly-TCDA/ZnO (5 wt %) powders prepared in Experiment 1, no apparentdifference was observed.

Temperature dependent Raman spectroscopy of poly-TCDA and poly-TCDA/ZnOcomposites. Temperature dependent Raman spectroscopy was used to furtherinvestigate the thermochromism of poly-TCDA and/or poly-TCDA composites.With reference to FIGS. 14A-14B and 15A-15B, Raman spectra under heatingand cooling cycles in the 25° C. to 150° C. temperature range forpoly-TCDA and poly-TCDA-ZnO are shown. The Raman data were taken insteps of 10° C. from 30° C. to 150° C. and also recorded in 10° C. stepsduring the cool down to room temperature. With reference to FIGS. 15Aand 15B, which depict the variable temperature Raman spectra ofpoly-TCDA-ZnO (2.5 wt %), in contrast to the variable temperaturespectra for pure poly-TCDA (FIGS. 14A-14B), a broad scattering band at690 cm⁻¹ appears in the spectra with increasing intensity as thetemperature is raised to form the red phase. Together with the ATI-FTIRresults, it is believed this may be due to the partial C═O of TCDA formsCOO⁻¹ with ZnO, and the amount of ionic characterized bond is not enoughto maintain the backbone structure of poly-TCDA under thermal stressapplied. The irreversible property caused by lack of enough ionic bondis solidified by the fact that the variable temperature Raman spectrashow the same intensity and no obvious wavenumber shifting for C≡C andC═C modes on cooling which is coincident with the poly-TCDA/ZnO (5 wt %)of Experiment 1. The wavenumber of C≡C, C═C as a function of temperatureis shown in FIGS. 16A-16B.

Differential Scanning Calorimetry (DSC) measurements. Now referring toFIGS. 17A-D, DSC measurements were performed to provide furtherinvestigation of the nature of interaction between TCDA/poly-TCDA andZnO. DSC data were obtained for pure TCDA monomer, poly-TCDA, andpoly-TCDA-ZnO, at heating and cooling rates of 10° C. min⁻¹ between 25°C. and 300° C. The heating scan for pure TCDA in FIG. 17A shows anendothermic peak at 61° C. due to melting. On cooling, (scan not shown)down-shifted exothermic crystallization peaks at 59° C. due tohysteresis were observed. FIG. 17B shows an endothermic peak at 61° C.due to melting of the unpolymerized monomer. A broad endotherm with ashoulder at 154° C. and a peak 190° C. are assigned to the melting ofpoly-TCDA. On cooling (scan not shown), polymer crystallization isindicated by broad exothermic features at 159° C. and 194° C. which areupshifted due to hysteresis relative to the corresponding endothermicmelting peaks. Crystallization of unpolymerized monomer were notobserved during the cooling cycle probably due to loss of the monomer bysublimation during thermal cycling. The heating scan for poly-TCDA-ZnO(FIG. 17D) shows an endotherm at around 57° C. due to unpolymerizedmonomer and a new endothermic feature at 132° C. due to melting of themonomer modified by the chelate formation discussed above, the broadexothermic features between 159° C. and 209° C. which could refer tothat of poly-TCDA are assigned to the melting of poly-TCDA. The newendothermic peak in poly-TCDA-ZnO is consistent with the FTIR andtemperature dependent Raman spectra discussed above suggesting aninteraction of ZnO particles with the head group of the polymerside-chain to form a chelate which can be schematically written as:Zn²⁺(COO⁻)₂. The temperature dependent Raman and DSC results alsoindicate the inkjet printing does not affect the interaction betweenTCDA and ZnO. On depositing material on a substrate, the ZnO particlesare uniformly distributed.

Optical densitometry. Now referring to FIG. 18, changes in chromaticityas a function of temperature for different samples are depicted. Therapid increase followed by a drop of the chromaticity of poly-TCDA iscaused by the chromatic transition near 70° C. For poly-TCDA with 2.5 wt% ZnO, the chromatic transition temperature increases to 110° C. Thepoly-TCDA film fabricated by the disclosed inkjet printing methods isvery similar to that of poly-TCDA prepared according to Experiment 1,however, the chromaticity of the poly-TCDA/ZnO film reaches a maximum at110° C. which is 10° C. lower than that of poly-TCDA/ZnO (5 wt %). Thediscrepancy is probably caused by the lower concentration of ZnO to formchelate. Because there is not enough ionic bond between Zn²⁺ and thehead group of TCDA to assist the thermal-stress release, reversiblecolor change of poly-TCDA/ZnO could be limited under certaintemperature. According to the temperature dependent Raman spectra andchromaticity as a function of temperature plots, 80° C. may be asuitable temperature at which the thin film bears the reversibility ofchromatic transition.

Now referring to FIG. 19, differences of chromaticity of material inblue phase and red phase after every five heating-cooling cycles areshown. Poly-TCDA barely bears chromatic reversibility after the firstfive cycles (by naked eye), and after 20 cycles the difference ofchromaticity at 80° C. and 25° C. cannot be differentiated by opticaldensitometer. By contrast, poly-TCDA-ZnO demonstrates a fairly goodchromatic reversibility until 40 thermal cycles.

Now referring to FIGS. 20A-D, poly-TCDA/poly-TCDA-ZnO samples fabricatedby inkjet printing on paper which were used for the chromaticitymeasurement are depicted. FIGS. 20A and 20B demonstrate the color ofpoly-TCDA-ZnO at room temperature and 80° C. (poly-TCDA are not shown),respectively. For poly-TCDA-ZnO (FIG. 20C) at 25° C., after 40 cycles, apartial region is red color (by naked eye), which could be caused by thelack of ZnO to strengthen the poly-TCDA backbone. That red region couldbe responsible for the increase of chromaticity of poly-TCDA-ZnO at roomtemperature after certain thermal cycles. FIG. 20D shows the inkjetprinted poly-TCDA after 5 thermal cycles. The small blue region couldexplain the chromaticity difference in FIG. 19.

QR Codes

A QR code is a kind of matrix symbol, which was developed by the companyDenson-Wave in 1994. Compared with conventional bar codes, QR code hasthe following features:

Large data capacity: A QR code can store 7,089 numeric characters and4,296 alphanumeric characters, and 1,817 kanji characters;

Fast speed scanning: A mobile phone with camera function can obtain thecontent from a QR code quickly and easily;

Small printout size: QR codes carry data both horizontally andvertically, thus QR codes are better than 1D barcodes in data capacity;

Advance error correcting: Even if 50% areas of code are damaged, QRcodes still can be recognized correctly;

Freedom of direction in scanning: The scanning direction of QR code isarbitrary.

While QR codes have become a standard for tracking, sorting andcataloging inventory, the functionality and utility could be increasedby incorporating a sensory capability within the QR code.

Provided herein are QR codes and methods of producing same including oneor more portions of the QR code including a chromatic ink to sensevarious stimuli such as temperature, stress and chemical presence. Withreference to FIGS. 21A and 21B, thermal sensor type QR codes are shownas 1 inch×1 inch codes printed on conventional printing paper. Oneskilled in the art will recognize the inventive QR codes may be anysuitable size and printed on any suitable substrate. These “Smart” QRcodes may be read by a color sensitive QR code reader and not onlyrecognize an information storage pattern but also a specifictemperature. In the embodiments shown, only a portion of the designedpattern is printed using poly-TCDA/ZnO composites or poly-TCDA as athermal sensor. The rest of the pattern is printed out with black ink.The QR code shows the ability of temperature sensing (from 25° C. to 80°C.) and the chromatic transition is reversible (for TCDA/ZnOcomposites). While not show, irreversible color change type poly-TCDA QRcode has been successfully inkjet printed. It will be apparent to theskilled artisan that the entirety of the QR code may be printed usingpoly-TCDA/ZnO composites or poly-TCDA as a thermal sensor.

Although the systems and methods of the present disclosure have beendescribed with reference to exemplary embodiments thereof, the presentdisclosure is not limited thereby. Indeed, the exemplary embodiments areimplementations of the disclosed systems and methods are provided forillustrative and non-limitative purposes. Changes, modifications,enhancements and/or refinements to the disclosed systems and methods maybe made without departing from the spirit or scope of the presentdisclosure. Accordingly, such changes, modifications, enhancementsand/or refinements are encompassed within the scope of the presentinvention. All references cited and/or listed herein are incorporated byreference herein in their entireties.

REFERENCES

-   1. Champaiboon, T.; Tumcharern, G.; Potisatityuenyong, A.;    Wacharasindhu, S.; Sukwattanasinitt, M., A polydiacetylene    multilayer film for naked eye detection of aromatic compounds.    Sensors and Actuators B: Chemical 2009, 139 (2), 532-537.-   2. Descalzo, A. B.; Dolores Marcos, M.; Monte, C.; Martinez-Manez,    R.; Rurack, K., Mesoporous silica materials with covalently anchored    phenoxazinone dyes as fluorescent hybrid materials for vapour    sensing. Journal of Materials Chemistry 2007, 17 (44), 4716-4723.-   3. Janzen, M. C.; Ponder, J. B.; Bailey, D. P.; Ingison, C. K.;    Suslick, K. S., Colorimetric Sensor Arrays for Volatile Organic    Compounds. Analytical Chemistry 2006, 78 (11), 3591-3600.-   4. Lu, Y.; Yang, Y.; Sellinger, A.; Lu, M.; Huang, J.; Fan, H.;    Haddad, R.; Lopez, G.; Burns, A. R.; Sasaki, D. Y.; Shelnutt, J.;    Brinker, C. J., Self-assembly of mesoscopically ordered chromatic    polydiacetylene/silica nanocomposites. Nature 2001, 410 (6831),    913-917.-   5. Muro, M. L.; Daws, C. A.; Castellano, F. N., Microarray pattern    recognition based on PtII terpyridyl chloride complexes: vapochromic    and vapoluminescent response. Chemical Communications 2008, (46),    6134-6136.-   6. Rakow, N. A.; Suslick, K. S., A colorimetric sensor array for    odour visualization. Nature 2000, 406 (6797), 710-713.-   7. Robert, W. C.; Darryl, Y. S.; Matthew, S. M.; Eriksson, M. A.;    Alan, R. B., Polydiacetylene films: a review of recent    investigations into chromogenic transitions and nanomechanical    properties. Journal of Physics: Condensed Matter 2004, 16 (23),    R679.-   8. Yuan, W.; Jiang, G.; Song, Y.; Jiang, L., Micropatterning of    polydiacetylene based on a photoinduced chromatic transition and    mechanism study. Journal of Applied Polymer Science 2007, 103 (2),    942-946.-   9. Hammond, P. T.; Rubner, M. F., Thermochromism in Liquid    Crystalline Polydiacetylenes. Macromolecules 1997, 30 (19),    5773-5782.-   10. Huang, X.; Jiang, S.; Liu, M., Metal Ion Modulated Organization    and Function of the Langmuir-Blodgett Films of Amphiphilic    Diacetylene: Photopolymerization, Thermochromism, and Supramolecular    Chirality. The Journal of Physical Chemistry B 2004, 109 (1),    114-119.-   11. Peng, H.; Tang, J.; Pang, J.; Chen, D.; Yang, L.; Ashbaugh, H.    S.; Brinker, C. J.; Yang, Z.; Lu, Y., Polydiacetylene/Silica    Nanocomposites with Tunable Mesostructure and Thermochromatism from    Diacetylenic Assembling Molecules. Journal of the American Chemical    Society 2005, 127 (37), 12782-12783.-   12. Peng, H.; Tang, J.; Yang, L.; Pang, J.; Ashbaugh, H. S.;    Brinker, C. J.; Yang, Z.; Lu, Y., Responsive Periodic Mesoporous    Polydiacetylene/Silica Nanocomposites. Journal of the American    Chemical Society 2006, 128 (16), 5304-5305.-   13. Ahn, D. J.; Chae, E.-H.; Lee, G. S.; Shim, H.-Y.; Chang, T.-E.;    Ahn, K.-D.; Kim, J.-M., Colorimetric Reversibility of    Polydiacetylene Supramolecules Having Enhanced Hydrogen-Bonding    under Thermal and pH Stimuli. Journal of the American Chemical    Society 2003, 125 (30), 8976-8977.-   14. Kim, J.-M.; Lee, J.-S.; Choi, H.; Sohn, D.; Ahn, D. J., Rational    Design and in-Situ FTIR Analyses of Colorimetrically Reversibe    Polydiacetylene Supramolecules. Macromolecules 2005, 38 (22),    9366-9376.-   15. Lee, S.; Kim, J. M., alpha-cyclodextrin: A molecule for testing    colorimetric reversibility of polydiacetylene supramolecules.    Macromolecules 2007, 40 (26), 9201-9204.-   16. Park, H.; Lee, J. S.; Choi, H.; Ahn, D. J.; Kim, J. M., Rational    Design of Supramolecular Conjugated Polymers Displaying Unusual    Colorimetric Stability upon Thermal Stress. Advanced Functional    Materials 2007, 17 (17), 3447-3455.-   17. Yuan, Z.; Lee, C.-W.; Lee, S.-H., Reversible Thermochromism in    Hydrogen-Bonded Polymers Containing Polydiacetylenes. Angewandte    Chemie 2004, 116 (32), 4293-4296.-   18. Gu, Y.; Cao, W.; Zhu, L.; Chen, D.; Jiang, M., Polymer mortar    assisted self-assembly of nanocrystalline polydiacetylene bricks    showing reversible thermochromism. Macromolecules 2008, 41 (7),    2299-2303.-   19. Song, J.; Cisar, J. S.; Bertozzi, C. R., Functional    Self-Assembling Bolaamphiphilic Polydiacetylenes as Colorimetric    Sensor Scaffolds. Journal of the American Chemical Society 2004, 126    (27), 8459-8465.-   20. Li, L. S.; Stupp, S. I., Two-Dimensional Supramolecular    Assemblies of a Polydiacetylene. 2. Morphology, Structure, and    Chromic Transitions. Macromolecules 1997, 30 (18), 5313-5320.-   21. Yang, Y.; Lu, Y.; Lu, M.; Huang, J.; Haddad, R.; Xomeritakis,    G.; Liu, N.; Malanoski, A. P.; Sturmayr, D.; Fan, H.; Sasaki, D. Y.;    Assink, R. A.; Shelnutt, J. A.; van Swol, F.; Lopez, G. P.;    Burns, A. R.; Brinker, C. J., Functional Nanocomposites Prepared by    Self-Assembly and Polymerization of Diacetylene Surfactants and    Silicic Acid. Journal of the American Chemical Society 2003, 125    (5), 1269-1277.-   22. Baughman, R. H., Solid-state polymerization of diacetylenes.    Journal of Applied Physics 1972, 43 (11), 4362-4370.-   23. Lim, K. C.; Heeger, A. J., Spectroscopic and light scattering    studies of the conformational (rod-to-coil) transition of    poly(diacetylene) in solution. The Journal of Chemical Physics 1985,    82 (1), 522-530.-   24. Chance, R. R.; Baughman, R. H.; Muller, H.; Eckhardt, C. J.,    Thermochromism in a polydiacetylene crystal. The Journal of Chemical    Physics 1977, 67 (8), 3616-3618.-   25. Patlolla, A.; Zunino, J.; Frenkel, A. I.; Iqbal, Z.,    Thermochromism in polydiacetylene-metal oxide nanocomposites.    Journal of Materials Chemistry 2012, 22 (14), 7028-7035.-   26. Lim, C.; Sandman, D. J.; Sukwattanasinitt, M., Topological    Polymerization of tert-Butylcalix[4]arenes Containing Diynes.    Macromolecules 2007, 41 (3), 675-681.-   27. D. Tobjörk, R. Osterbacka, Paper Electronics, Advanced    Materials, 23(2011) 1935-1961.-   28. L. Nyholm, G. Nyström, A. Mihranyan, M. Stromme, Toward Flexible    Polymer and Paper-Based Energy Storage Devices, Advanced Materials,    23(2011) 3751-3769.-   29. A. C. Siegel, S. T. Phillips, M. D. Dickey, N. Lu, Z. Suo, G. M.    Whitesides, Printable Electronics: Foldable Printed Circuit Boards    on Paper Substrates (Adv. Funct. Mater. January 2010), Advanced    Functional Materials, 20(2010) n/a-n/a.-   30. U. Zschieschang, T. Yamamoto, K. Takimiya, H. Kuwabara, M.    Ikeda, T. Sekitani, et al., Organic Electronics on Banknotes,    Advanced Materials, 23(2011) 654-658.-   31. A. Russo, B. Y. Ahn, J. J. Adams, E. B. Duoss, J. T.    Bernhard, J. A. Lewis, Pen-on-Paper Flexible Electronics, Advanced    Materials, 23(2011) 3426-3430.-   32. M. C. Barr, J. A. Rowehl, R. R. Lunt, J. Xu, A. Wang, C. M.    Boyce, et al., Direct Monolithic Integration of Organic Photovoltaic    Circuits on Unmodified Paper, Advanced Materials, 23(2011)    3500-3505.-   33. J. Jang, J. Ha, J. Cho, Fabrication of Water-Dispersible    Polyaniline-Poly(4-styrenesulfonate) Nanoparticles For    Inkjet-Printed Chemical-Sensor Applications, Advanced Materials,    19(2007) 1772-1775.-   34. J.-H. Kang, Z. Xu, S.-M. Paek, F. Wang, S.-J. Hwang, J. Yoon, et    al., A Dual-Polymer Electrochromic Device with High Coloration    Efficiency and Fast Response Time:    Poly(3,4-(1,4-butylene-(2-ene)dioxy)thiophene)—Polyaniline ECD,    Chemistry—An Asian Journal, 6(2011) 2123-2129.-   35. B. J. de Gans, P. C. Duineveld, U. S. Schubert, Inkjet Printing    of Polymers: State of the Art and Future Developments, Advanced    Materials, 16(2004) 203-213.-   36. T. H. J. van Osch, J. Perelaer, A. W. M. de Laat, U. S.    Schubert, Inkjet Printing of Narrow Conductive Tracks on Untreated    Polymeric Substrates, Advanced Materials, 20(2008) 343-345.-   37. Y. Oh, J. Kim, Y. J. Yoon, H. Kim, H. G. Yoon, S.-N. Lee, et    al., Inkjet printing of Al2O3 dots, lines, and films: From uniform    dots to uniform films, Current Applied Physics, 11(2011) S359-S363.-   38. J. K. Lee, U. J. Lee, M.-K. Kim, S. H. Lee, K.-T. Kang, Direct    writing of semiconducting polythiophene and fullerene derivatives    composite from bulk heterojunction solar cell by inkjet printing,    Thin Solid Films, 519(2011) 5649-5653.-   39. B. Yoon, D.-Y. Ham, O. Yarimaga, H. An, C. W. Lee, J.-M. Kim,    Inkjet Printing of Conjugated Polymer Precursors on Paper Substrates    for Colorimetric Sensing and Flexible Electrothermochromic Display,    Advanced Materials, 23(2011) 5492-5497.-   40. J. Chuang, Y. Hu, H. Ko, A Novel Secret Sharing Technique Using    QR Code, International Journal of Image Processing. 4(2010) 468-475.

What is claimed is:
 1. A thermochromically reversible compositioncomprising 6 to 99.5 wt % of TCDA and ZnO nanoparticles wherein the ZnOnanoparticles have an average particle size of 0.01-99 nm.
 2. Thecomposition according to claim 1 comprising 20 to 99.5 wt % of TCDA. 3.The composition according to claim 1 comprising 50 to 97.5 wt % of TCDA.4. The composition according to claim 1 comprising 85 to 97.5 wt % ofTCDA.
 5. The composition according to claim 1 comprising 0.5 to 94.0 wt% of ZnO.
 6. The composition according to claim 1 comprising 0.5 to 80.0wt % of ZnO.
 7. The composition according to claim 1 comprising 2.5 to50.0 wt % of ZnO.
 8. The composition according to claim 1 comprising 2.5to 15.0 wt % of ZnO.
 9. The composition according to claim 1 wherein theZnO nanoparticles have an average particle size of 0.1-99 nm.
 10. Thecomposition according to claim 1 wherein the ZnO nanoparticles have anaverage particle size of 0.1-15 nm.
 11. The composition according toclaim 1 consisting of TCDA and 0.5-94 wt % of ZnO.
 12. The compositionaccording to claim 1 consisting of TCDA and 0.5 to 80.0 wt % of ZnO. 13.The composition according to claim 1 consisting of TCDA and 2.5 to 50.0wt % of ZnO.
 14. The composition according to claim 1 consisting of TCDAand 2.5 to 15.0 wt % of ZnO.
 15. The composition according to claim 1wherein the TCDA comprises poly-TCDA.
 16. A thermochromically reversiblefilm sensor comprising poly-TCDA and ZnO nanoparticles disposed on asubstrate wherein the ZnO nanoparticles have an average particle size of0.01-99 nm and the film comprises 6 to 99.5 wt % of TCDA.
 17. Thethermochromically reversible film sensor according to claim 16comprising the substrate and a film consisting of poly-TCDA and ZnOnanoparticles disposed on a substrate wherein the ZnO nanoparticles havean average particle size of 0.01-99 nm.
 18. The thermochromicallyreversible film sensor according to claim 16 wherein the film consistsof TCDA and 0.5-94 wt % of ZnO.
 19. The thermochromically reversiblefilm sensor according to claim 16 comprising a QR code.
 20. A method ofmaking a thermochromically reversible film comprising applying athermochromically reversible composition comprising 6 to 99.5 wt % ofTCDA and ZnO nanoparticles wherein the ZnO nanoparticles have an averageparticle size of 0.01-99 nm to a substrate and subjecting thethermochromically reversible composition to UV irradiation for aduration sufficient to convert at least a portion of the TCDA topoly-TCDA.
 21. The method according to claim 20 comprising applying thethermochromically reversible composition to a substrate using an inkjetprinter.